| 摘要 |
An adaptive window Fourier phase extraction method in optical three-dimensional measurement comprises the following steps: (1) projecting a gray-scale sinusoidal fringe pattern on an object to be measured, and a CCD collecting a formed deformed fringe pattern; (2) performing empirical mode decomposition on the deformed fringe pattern by row to obtain a series of intrinsic mode functions and a residual component as a decomposition result for each row; (3) performing Hilbert transform on each intrinsic mode function of signals by row to obtain a corresponding instantaneous frequency and a marginal spectrum, and determining, through analysis of the marginal spectrum, the instantaneous frequency capable of accurately describing change of the fringe pattern; (4) determining a background component of a fringe signal by row; (5) adaptively locating a local stable region of the fringe signal by row using the determined instantaneous frequency; (6) removing the background component from the original fringe pattern by row to obtain a new signal; (7) in each local stable region, performing adaptive window Fourier transform on the new signal by row, to obtain distribution of a wrapped phase of the fringe signal; and (8) unwrapping the wrapped phase to obtain an absolute phase and converting the absolute phase into height information, thereby implementing three-dimensional measurement of the object. The phase extraction method has strong adaptability and high robustness, thereby greatly improving the measurement precision of an object having a complex surface or abrupt edges. |
